Ianieva O. Interactions of multiply metal-resistant bacteria with ions of copper, cadmium and vanadium

The final objective of the thesis was to study interactions of multiply metal-resistant bacteria and ions of copper, cadmium and vanadium. 110 strains of microorganisms resistant to high levels of copper, cadmium, silver and pentavalent vanadium have been isolated from sites with different level of technogenic influence. The presence of microorganisms resistant to high levels of copper, cadmium, silver and vanadium in the sites with both low and high level of technogenic influence has been shown. Gram-negative bacteria were prevalent among the isolated strains. The new habitats of vanadate-reducing microorganisms have been found. Most isolated strains were multiply metal-resistant. The multiple metal resistance phenotypes CuV (60%), CdV (50.9%), VAg (44.5%) were predominant among the isolated microorganisms. Three strains with highest multiple resistance to heavy metal ions have been identified as Pseudomonas aeruginosa. Copper and cadmium resistance of A17 and A03 strains was shown to be inducible while that of A17 strain was constitutive. Vanadate resistance of C25a strain was inducible. Heavy metal ions either stimulated or inhibited the exopolysaccharide production by P. aeruginosa strains. The strains P. aeruginosa A17, A03 and C25a assimilated oil, diesel oil and hexadecane as a sole carbon source. Genetic determinants of copper and cadmium resistance have been transferred by conjugation from P. aeruginosa C25a strain to Escherichia coli J53. Copper and cadmium resistance of multiresistant P. aeruginosa strains was determined by two different mechanisms - sorption processes on the cell surface and ATP-dependent efflux systems. P. aeruginosa strains have been shown to reduce up to 60% vanadate under microaerophilic conditions. Vanadate reduction started after the active phase growth. This process did not represent anaerobic respiration. The possibility that vanadate reduction was the result of a spontaneous process has been eliminated. This is the first report of induction of bacterial vanadate reduction under aerobic conditions by ATPase inhibitor dicyclohexylcarbodiimide. The obtained results can provide new insights into the mechanisms of bacterial heavy metal resistance.